Method of producing hollow set-screws.



N. W. CUMMINS.

APPLICATION FILED DEC. 0. 9 7. 1,243,818, Patented 0013. 23.1917.

NORMAN w. cummms, or nnrncnrom, oofiiwnc'rrour, nssrenon TO THE norms a nnssrcx country, or nnrnenronr, comrncrrcur, a oonronn'rron or con- 11 EC'I'ICUT.

Specification of Letters Patent.

METHOD OF PRODUCING HOLLOW SET-SCREWS. v

Patented 0 011.23, 1917.

Application filed December 14, 1914, Serial lilo. 877,177. Renewed March 20, 1917. Serial No. 156,226.

To all whom it may concern ing had to the annexed drawlngs, whereinz' Figure 1 is a sectional view of the die in which the stock from which the screw is formed is placed, the stock and the knockout punch or die being shown in full;

Fig. 2 a similar view, the partially-formed screw-blank being shown in section and the initial forming punch in full;

Fig. 3 a like view with the final forming punch in position;

Fig. 4 a sectional view of a screw formed from a blank subjected to the action of but a single punch; and

Fig. 5 a similar view of a screw formed as the result of the successive action of a series of punches.

In the drawings, 1 denotes the die, having a recess 2 therein, cylindrical in cross-section, open. at the top and having a downwardly-inclined or tapering bottom 3. An opening 4 extends through the lower portion of the die, terminating in the center of the bottom 3. A knockout die 5 extends through said opening 4 and projects into the die cavity, the upper end of said die 5 being rounded, as at 6. Aswill be seen upon ref- (indicated by 7, Fig. 1) is cylindrical in shape, and will preferably be cut from a rod or wire of circular cross-section and of a diameter substantially equal to that of the die-recess 2. It is dropped into said recess and the lower end thereof comes to rest upon purpose which will pres- A punch 8, having its lower end 9 pothe upper rounded end 6 of the knock-out Be it known that I, NORMAN W. CUM- d' lygonal in crosssection (preferably hexagonal) and its extreme lower end slightly convex, is forced centrally into the upper end of the blank, whereby the metal is caused to flow both downwardly and upwardly, filling the space in the lower portion of the die and likewise passing upwardly aboutthe polygonal portion'of the punch. Such operation will form a screw (minus the the removal of the screw-blank from the A threads, which, of course, are formed after die) such as is shown in Fig. 4. This screw may be all-sufficient for. certain purposes, but preferably I carry the process further, whereby a deeper recess or sink is formed in the screw-blank, while at the same time the metal is more thoroughly condensed and the upper edgeis likewise given a better finish. To this end I employ a second punch, 10, the lower end 11 of which is of the same outline as the end '9, but is of slightly smaller diameter, say, one-sixty fourth of an inch, while at the same time said punch, above the polygonal portion, is provided with a shoulder 12, the punch-body above said shoulder substantially filling the die-recess 2. Said second punch 10 is forced downwardly in the previously-formed opening in the stock, sinking into the stock, and causing a further flow of the metal, both upwardly and around the polygonal section 11, the shoulder 12 finally coming into contact with the upper edge of the metal, whereby the central depression in the stock is deepened and the metal further condensed by being forced into contact with the side faces of the section 11 and shoulder 12.

The action of the punch swages the metal into close and intimate contact with the walls of the die, over the rounded end of the knock-out die 5, and also about itself, whereby the upper edge of the screw-blank is finished by the shoulder, and the interior faces 13 of the countersink are rendered smooth. Upon the completion of the sinking of the punch 10, the knock-out or kickout die 5 is actuated in an upward direction, thereby removing the screw-blank from the recess 2 of die 1. It will be found that the lower end of the blank will present a also against the depression 16,formed by the rounded end 6 of the kick-out die 5, so that it will set or adapt itself closely to any surface against which it may be forced.

It is, of course, conceivable that instead of forming the lower end of the screw with a cupped or depressed portion, the knockout die may be omitted and the bottom of the die-recess continued down to a sharp point, in which case the screw-blank would present a pointed lower end.

The final step in the process of forming the screw is to thread the same exteriorly.

A set-screw made in accordance with the above method is homogeneous throughout, owing to the fact that it is formed from a solid piece of metal and swaged into shape. The threads, when cut, are sharp and smooth without the slightest trace of a pit or chatter, indicating an exceedingly dense structure.

Having thus described my invention, what I claim is:

1. The process of making hollow setscrews, which. consists in placing a solid piece of stock of substantially cylindrical form in a die having. the same cross-section and likewise having a tapering bottom; sinking a punch into the stock, thereby causing the metal to flow upwardly about said punch and also downwardly to conform to the bottom of the die; and finally threading the blank thus produced. M

2. The process of making hollow setscrews, which consists in placing a solid, substantially cylindrical piece of stock in a die having a cross-section of like contour, and likewise having a downwardly-tapering bottom; sinking a punch, polygonal in crosssection, downwardly into the central upper portion of the stock, thereby causing the laterally confined stock to How upwardly about the punch and to the bottom of the die; and finally threading the blank thus produced.

3. The process of making hollow setscrews, which consists in placing a solid cylindrical piece of stock in a. die having a cross-section of like contour; thereafter sinking a punch, polygonal in cross-section, into the upper central portion of the stock; then sinking a second punch of like but somewhat smaller dimensions into the opening produced by the first punch, said second punch likewise having a shouldered portion above the polygonal section, whereby the upper marginal portion of the stock, as well as the bodythereof, will be condensed as the punch reaches its limit of inward movement; and finally threading the blank thus produced.

4. The process of making hollow setscrews, which consists in placing a solid cytact with the upper edge of the wall of the also downwardly to conform measles lindrical piece of stock in a die having a cross-section of like contour and a tapering bottom; thereafter, while the stock is confined in the die, causing the same to flow downwardly to fill the bottom of the die and likewise upwardly about a punch sunk downwardly into the upper face of the stock; and finally threading the blank thus produced.

5. The process of making hollow setscrews, which consists in placing a solid cylindrical piece of stock in a die having a cross-section of like contour; then subjecting the stock to the action of a punch having a polygonal cross-section; then to a punch of like but smaller cross-section, said punch having an outwardly-projecting shoulder above its punching portion, adapted to conblank toconfine and condense the same; and g5 finally threading the blank thus formed.

6. The process of making hollow setscrews, which consists in placing a solid cylindrical piece of metal stock in a die having a cross-section of like form, said die likewise having a downwardly-inclined, tapering bottom, with a centrally-disposed opening therein; projecting 'a kick-out die, having a rounded upper end, through said opening and into contact with the lower face of the stock; then sinking a punch into the up per face of the stock, whereby the metal will be caused to flow to fill the lower portion of the die and around the kick-out die, and likewise caused to flow upwardly into the oo space between the cylindrical wall of the die and the punch; and finally threading the screws, which consists in placing a solid piece of-stock in a laterally-confining die; sinking a punch into one end thereof, whereby it will be elongated and a sink formed in one end; then sub ecting the stock to a punch of smaller diameter and thereby causing fur- 11o ther elongation of the blank and an inward movement of the 'metal thereof into contact with the punch; and finally exteriorly threading the blank thus produced.

' 8. The process of making hollow setscrews, which consists in placing a solid piece of stock in a laterally-confining die; Y sinking a punch, polygonal in cross-section, intoone end of the stock, whereby the'stock will be forced into contact with the bottom 'of the die and likewise elongated and caused to How up about the punch; then sinking a punch of like but smaller crosssection into the opening or sink formed by the first punch, and simultaneously confinstock and simultaneously shaping the lower end thereof; then deepening and. contracting the sink and simultaneously swaging the upper end of the blank being formed; and finally exteriorly threading the blank thus produced.

10. The process of making hollow'setscrews, which consists in producing a sink in one end of a piece of stock and simultaneously forming a cup-shaped recess in the opposite end of the screw-blank and at the same time elongating the stock; then swaging the blank to'contract and elongate the sink and to finish blank; and finally exteriorly threading the blank thus produced.

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses.

NORMAN W. OUMMINS. Witnesses:

F. W. SMITH, J r., M. T.' LONGDEN.

the upper edge of the 15V 

